That Carter TQ is one of the best performing carbs ever built, when it's right. Unfortunately some have been unintentionally overheated which can distort the phenolic plastic section. That can cause air leaks, which can cause whistling.

The best/easiest way to track down your sound is by using a piece of tubing as a stethoscope to pinpoint the source. Common sense for safety is a given.

If it's a warped body causing leaks you may be able to true it up on a sheet of fine abrasive on a flat metal or glass surface to deck it. Sealers can cause some problem later if rebuilding but can help as a last resort. If you rebuild it first it can forestall the need to tear it down again for a long time.

A high-miler carb might have some leakage at throttle shaft bores in aluminum carb body causing whistling. These can be drilled out and a plastic spacer inserted, as a bearing & seal. Spacer OD to fit carb body & spacer ID to fit throttle shaft. UHMW plastic works very well for this, but the machining is a little tricky. It can be worked with hand tools.

I always used a phenolic or aluminum or even sealed wood spacer between a TQ & manifold to stop the heat path, and of course an aluminum intake manifold helps.

By the way, that carb should have 2 independent vacuum circuits, one ported & one full manifold vacuum. All nipples on the carb either need a vacuum tube connected or else a flexible plastic/rubber cap on them. You might want to check the history on that carb. If it's from somewhere in the deep south then make sure it ain't just whistling Dixie.